The function of levelers in the electrodeposition of copper varies with the object of deposition. In the Damascene process for filling submicron features of semiconductor integrated circuit devices, levelers, accelerators and/or suppressors are combined in appropriate concentrations in the plating bath to promote bottom-up filling of such features. In such applications, the function of the additives is to establish a vertical polarization gradient along the wall of a via or trench which enhances the current density at the bottom relative to the current density in the upper reaches of the wall and on the field.
Levelers also find application in electrodeposition compositions for filling so-called through silicon vias (TSVs) which are very small on an absolute scale, but far larger than the submicron features that are filled in the Damascene process.
Levelers are also used in electrolytic solutions for plating copper onto printed circuit boards, including the walls of through holes in the board. In such applications, levelers function to enhance throwing power in conformal plating of the walls and surrounding field.
As described in U.S. Pat. No. 4,336,114 to Mayer et al., the subject matter of which is herein incorporated by reference in its entirety, poly(epichlorohydrin) quaternized by reaction with trimethylamine or triethylamine has been used in combination with a phthalocyanine, an organic divalent sulfur compound, and an alkylated polyethylenimine in aqueous compositions for the electrodeposition of copper to produce copper deposits that are said to be bright, ductile, and level with good recess brightness on metal substrates, particularly printed circuit boards, over a wide range of bath concentrations and operating current densities. The brightening and leveling systems are particularly applicable for copper plating of electronic circuitry printed circuit boards in achieving bright, level, ductile deposits which provide level deposits over imperfections in the apertures of such printed circuitry boards.
U.S. Pat. No. 4,555,315 to Barbieri et al., the subject matter of which is herein incorporated by reference in its entirety, describes a similar process using a plating bath comprising a bath soluble polyether compound, a bath soluble organic divalent sulfur compound, a bath soluble adduct of a tertiary alkyl amine with poly(epichlorohydrin), and a bath soluble reaction product of polyethyleneimine and an alkylating agent.
U.S. Pat. No. 6,183,622 to Janik, the subject matter of which is herein incorporated by reference in its entirety, describes the use of poly(epichlorohydrin) trimethylamine quaternary additives that enhances the ductility of copper deposited in electrorefining or electrowinning.
U.S. Pat. No. 6,676,823 to Bokisa, the subject matter of which is herein incorporated by reference in its entirety, describes the use of an adduct of alkylamine and poly(epichlorohydrin) as a brightener in acid copper plating, including high speed plating using relatively high current densities. A list of applications includes plating integrated circuits and through holes of circuit boards.
U.S. Pat. No. 7,777,078 to Kumagai et al., the subject matter of which is herein incorporated by reference in its entirety, describes a process for plating copper foil onto a cathode drum. The plating bath may contain poly(epichlorohydrin) quaternary amine salts. Quaternizing amines include trimethylamine and triethylamine.
U.S. Pat. Pub. No. 2006/0062753 to Naraghi, the subject mater of which is herein incorporated by reference in its entirety, describes the use of poly(quaternary ammonium) salts as biodegradable corrosion inhibitors for metal surfaces, and as biocides. Exemplary tertiary amines which may be quaternized by reaction with poly(epichlorohydrin) include hexadecyl-dimethylamine, tetradecyldimethylamine, dodecyldimethylamine, imidazoline, and alkyl pyridines. Epichlorohydrin is polymerized in the presence of a polyol, resulting in binding of the poly(epichlorohydrin) through ether linkages to the polyol residue. Epichlorohydrin repeating units of the polymer are then reacted with the tertiary amine to produce quaternary ammonium pendent groups.